title: Synthesis and evaluation of conformationally restricted inhibitors of aspartate semialdehyde dehydrogenase.
abstract: Inhibitors of the enzyme aspartate semialdehyde dehydrogenase, a key biological target for the generation of a new class of antibiotic compounds, have been developed. To investigate improvements to binding within an inhibitor series, the lowering of the entropic barrier to binding through conformational restriction was investigated. A library of linear and cyclic substrate analogues was generated and computational docking used to aid in structure selection. The cyclic phosphonate inhibitor 18 was thus identified as complimentary to the enzyme active-site. Synthesis and in vitro inhibition assay revealed a K(i) of 3.8 mM against natural substrate, where the linear analogue of 18, compound 15, had previously shown no inhibitory activity. Two further inhibitors, phosphate analogue diastereoisomers 17a and 17b, were synthesised and also found to have low millimolar K(i) values. As a result of the computational docking investigations, a novel substrate binding interaction was discovered: hydrogen bonding between the substrate (phosphate hydroxy-group as the hydrogen bond donor) and the NADPH cofactor (2'-oxygen as the hydrogen bond acceptor).
authors.affiliation: Pharmaceutical Science Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, UK.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Evitt
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Cox
mesh_terms: D000595:Amino Acid Sequence; D001223:Aspartate-Semialdehyde Dehydrogenase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D003198:Computer Simulation; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009249:NADP / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000235:genetics; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D009249:NADP; D001223:Aspartate-Semialdehyde Dehydrogenase